P256E
Engine Idle Speed Selector Sensor/Switch Circuit Intermittent/Erratic
The idle-speed selector signal jumps or drops out — usually a worn rotary contact or vibration. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine light on
- Idle speed too high, too low, or unstable
- Possible stalling at idle or after cold start
Common causes
Ordered by how often each turns out to be the cause.
- Worn rotary contactCommon
- Connector with intermittent contact under vibrationLess likely
- Harness routed against vibrating componentLess likely
Parts involved
- Idle Speed Selector Switch
P256E is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.